In recent years, integrated circuits have become heightened in degree of integration, so that the microlithography for superfine patterns having a line width of half micron or below has come to be required in the production of semiconductor substrates for VLSI and the like. In order to meet such a requirement, the wavelengths used in an exposure apparatus for photolithography were getting shorter, and nowadays the use of far ultraviolet light in shorter wavelength region, or excimer laser beams (XeCl, KrF, ArF), is being investigated.
As the investigation progresses, it is of urgent necessity to develop new resist materials having less absorption at the above short wavelengths, satisfactory sensitivity and high dry-etching resistance. In particular, the exposure method using ArF excimer laser (wavelength: 193 nm) or the like is under consideration, and there is a pressing need of developing resist materials having excellent sensitivity and resolution in such a short wavelength region.
The chemically non-amplified resist composition described in JP-A-8-262717 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") is a resist composition having high dry-etching resistance, but this composition cannot answer the purpose of practical use because it has drawbacks in sensitivity, profile, adhesiveness to a substrate used for pattern formation and so on.
Further, the chemically amplified resist described in JP-A-6-214388, which comprises an acid generator, a cross-linking agent and a specific polyhydroxyl compound, is a negative working photoresist having high resolution. However, this negative working photoresist is insufficient in transparency and has drawbacks in sensitivity and profile, and so it is unsatisfactory from practical point of view.